MATHEMATICAL MODELLING OF A KENAF HARVESTER

Abstract

In this study, a mathematical model of the cutting behaviour of the kenaf harvester was developed by considering plant stems as uniform cantilever beam. The stems were visualized as being subjected to a cutting force by a cutting blade with (n) teeth, and the energy required to overcome the shear resistance of the stem by the cutting blade is equal to the energy required for quasi-static cutting and the energy expended on overcoming friction. The developed equation was used to predict the cutting torque, power and energy requirements of the machine during operation and validated on three kenaf varieties.

The result shows an increase in cutting torque of the plant stalk with crop maturity for all the varieties of kenaf. It also shows a consistent trend of increase in predicted and measured cutting power from 10.62 kW to 18.90 kW. There is an overall rise in predicted and the measured cutting energy for all varieties of the kenaf as the crop matures. The derivations between the values of predicted and measured cutting torque, power and energy is less than 10 %, which is within the allowable range of accepted E-values for model validation.